Many products, particularly food products, lose their freshness through age and oxidization. Even when these products are stored in generally air-tight containers, the air trapped within the container may actively participate in the oxidation process. Aging and decay is particularly rapid in fruit- and vegetable-based items due to high contents of oxygen-sensitive nutrients. For example, guacamole discolors within hours when in contact with open air, and rapidly reaches the end of its shelf life. Accordingly, a need exists for a container that preserves the freshness of food or other oxygen-sensitive products.